There are more than 12 million amateur baseball players in the United States. Injuries due to participation in organized baseball are common occurrences and are frequent reasons for seeking evaluation from health care specialists. Baseball and other throwing sports put tremendous stress on the shoulder and elbow. As more athletes play more baseball and softball at younger ages, Sports Medicine specialists see more and more elbow and shoulder pitching injuries. Preven­tion is important. Baseball pitching guidelines try to improve safety by limiting the pitch counts per week, per game, or per practice, based on the athlete’s age and skill level. A better un­derstanding of the causes of throwing injuries such as fatigue, poor throwing mechanics, and overuse are imperative in prevention and treatment of shoulder and elbow injuries.The most devastating throwing injury is a torn ulnar collateral ligament of the elbow (also known as the medial collateral ligament). Often this serious injury needs an elbow ligament reconstruction known as a “Tommy John” procedure. Ulnar collateral ligament tears can start slowly as an elbow sprain and progress steadily, or can happen all at once. Ulnar collateral ligament tears result in pain on the inner side of the elbow with throwing, and difficulty controlling the pitch. When the symptoms are mild, rest and medication may take care of the problem. However, if the athlete is unable to pitch due to the pain the “Tommy John” operation is needed.Shoulder injuries also plague pitchers and other throwers. . The repetitive stresses placed on the athlete’s shoulder joint complex during the throwing motion challenges the physiologic limits of the surrounding tissues. The most commonly injured structures are the capsule/ligaments, rotator cuff, and labrum. Often the rotator cuff can be strengthened to compensate for the injury, but sometimes the ligaments are too loose or there is a torn labrum and surgery is necessary.If the athlete complains of elbow or shoulder pain the day after throwing, or movement of the joint is painful or restricted compared to the opposite side, consult with a sports medicine physician or physical therapist who specializes with baseball injuries immediately. The preventative care and treatment of these athletes are challenging. Injury may occur because of muscle fatigue, muscle weakness, strength imbalances, loss of motion, soft tissue flexibility, alterations in throwing mechanics, and poor static stability. Because the overhead-throwing athlete is unique, the knowledge of the normal physical characteristics, biomechanics, and pathomechanisms of throwing-related injuries is imperative to accurately assess and treat potential injuries.